> an excise tax on number of servers

We need to go full Oracle and charge an excise tax per logical CPU core. For GPUs we can count SIMT lanes.

More seriously they should be taxed per watt, likely in an asymptotic manner because most of the externalities don't scale linearly. Any additional infrastructure requirements should be directly rolled into their electric and water bills, which is to say that they should receive a very unfavorable rate.